The invention relates generally to communication systems and, more particularly, to techniques for providing error detection/correction in packet-based communication systems.
Noisy communication channels, such as satellite uplink and downlink channels and terrestrial microwave channels, typically require the use of error correction coding to maintain a low bit error rate (BER) through the channel. Low BERs are required by certain communication applications to achieve a desired level of communication quality in the system. Some communication applications, however, are more tolerant of bit errors in the channel and can thus perform adequately using less coding than other applications. For example, applications involving video conferencing, high definition television (HDTV), Moving Picture Experts Group (MPEG) video, and vocoded voice can generally perform at higher BERs than other applications before the quality of the communication becomes intolerable.
Modern communication systems, most notably wireless systems, typically use a fixed amount of error correction coding within their communication links. Thus, when these systems are used to support multiple communications applications (e.g., voice, video, computer data, etc.), a level of error correction coding must be used that is capable of achieving at least a minimum acceptable performance level for applications that are least error tolerant. Thus, for more error tolerant applications, a higher coding rate is used than is required to achieve an acceptable or negotiated performance level. This xe2x80x9chigher than neededxe2x80x9d error coding rate results in a xe2x80x9clower than possiblexe2x80x9d throughput for the more error tolerant applications. In many such applications, however, it is desirable to achieve increased communication throughput at the expense of communication accuracy.
Therefore, there is a need for a method and apparatus that is capable of dynamically varying an error coding rate used in a communication channel based on varying system needs.